Brain

Batman explains to Marvin that even though not everyone has super strength, everyone has a brain

A brain is the most important part of the human and animal anatomy. The brain is what allows us to think, and sends data to the rest of our body so that we can do the things we need to do that are necessary for staying alive. Although most people use only a small percentage of their brain, people with super intelligence use much more. Even people with a genius level intellect use quite a bit of their brain as well.

Although most plant species do not have brains, some do, that is, they at least have the capacity to think, such as Plant Soldiers and Arborans.